1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Postharvest quality management of avocado (persea ameicana mill ) C V.Arka Supreme(Department of Postharvest Management, College of Agriculture, Vellanikkara, 2025-12-02) Miyandra Martin; Anu Mary MarkoseAvocado (Persea americana Mill) is a subtropical climacteric fruit originating from south-central Mexico and Guatemala that has gained global popularity owing to its rich nutritional composition. The fruit is valued for its high energy content, healthy monounsaturated fats that support heart health and is a good source of protein, potassium, and various vitamins. Despite its value, avocados are highly perishable due to their climacteric nature, characterised by a surge in ethylene production immediately after harvest, leading to rapid ripening and spoilage, within 5-6 days of storage, resulting in significant economic losses. The present study, entitled ‘Postharvest quality management of avocado (Persea americana Mill) cv. Arka Supreme’ was carried out at the Department of Postharvest Management, College of Agriculture, Vellanikkara, during 2023-2025 to standardise the postharvest treatments for delayed ripening and shelf life extension in avocado by the application of ethylene inhibitors and maintenance of optimum storage temperatures. The first experiment evaluated the efficacy of various ethylene inhibitors, including Salicylic acid (SA), Sodium nitroprusside (SNP), and 1- Methylcyclopropene (1-MCP) at different concentrations. The control fruits were spoiled and discarded after 6 days. SA and SNP treatments extended shelf life to 12 days, while 1-MCP treatments were superior, extending the shelf life to 15 days. Although statistical comparisons were made up to the 12th day (other treatments became unmarketable) fruits treated with 500 ppb 1-MCP remained marketable up to 15 days with highest quality attributes like lowest respiration rate (395.99 mg CO2 kg-1 h-1), ethylene production rate (88.95 μL kg-1 h-1), and physiological loss in weight (9.64 %) while maintaining the highest fruit firmness (1.86 kg cm-2), titratable acidity (0.2 %), total sugars (1.13 %), and moisture content (75.37 %) with the slowest increase in total soluble solids (7.15 °Brix) and oil content (9.91 %). Treated fruits also exhibited the highest retention of total phenolic content (75.51 mg 100 g-1), total flavonoids (32.87 mg 100 g-1), antioxidant activity (IC50 value 4.08), and peroxidase (POD) activity (1.9 U mL-1) with the lowest polyphenol oxidase (PPO) activity (3.16 U mL-1). The highest total score (60.9) in sensory evaluation also confirms 500 ppb 1-MCP as the most effective treatment. In the second experiment, the best treatment from the first experiment (500 ppb 1-MCP) was utilised to assess the effect of storage temperature on the quality and shelf life of avocado. The fruits stored under ambient temperature (30 ± 2 ℃) were discarded due to spoilage by the second week itself. Refrigerated storage (4-7 ℃) extended shelf life to 21 days, but caused severe chilling injury, negatively impacting quality. Cold storage (10 ± 2 ℃) was found to be the most effective in extending shelf life up to 37 days, retaining quality attributes like the lowest respiration rate (292.93 mg CO2 kg-1 h-1), ethylene production rate (27.25 μL kg-1 h-1), physiological loss in weight (7.57 %) and highest fruit firmness (1.98 kg cm-2). Total soluble solids (7.1 °Brix) and oil content (9.14 %) increased slowly, reaching peak values only by the 5th week. The treatment was also superior in retaining quality, with the highest titratable acidity (0.29 %), total sugars (1.21 %), moisture content (76.38 %), total phenolic content (78.52 mg 100 g-1), and total flavonoids (34.28 mg 100 g-1). It also maintained the highest antioxidant activity (IC50 value 4.09), peroxidase (POD) activity (1.97 U mL-1) and the lowest polyphenol oxidase (PPO) activity (3.09 U mL-1) along with the highest organoleptic score of 58.0 by the end of the 5th week. Pearson’s correlation analysis revealed strong relationships between ethylene production and other quality attributes of avocado. Ethylene evolution showed positive correlations with oil content, respiration rate, total soluble solids, and antioxidant activity, and negative correlations with firmness, titratable acidity, sugars, flavonoids, and moisture, indicating its key role in fruit ripening dynamics. The present study demonstrated that the combination of 1-MCP (500 ppb) and cold storage (10 ± 2 ℃) preserved the fruit’s physiological and biochemical quality by delaying the climacteric surge, successfully extending its shelf life from 6 days to 37 days. This research offers an effective strategy to mitigate postharvest losses and thereby promote a more stable and sustainable avocado supply chain.Item Post harvest characterisation and management of avocado(Persea americana Mill.)(Department of Post Harvest Technology, College of Agriculture, Vellanikkara, 2022) Geethu, M; Saji GomezAvocado is a subtropical fruit crop, belonging to the family Lauraceae, and is rich in proteins, vitamins, minerals and monounsaturated fatty acids such as oleic acid, contributing to its high nutritive and therapeutic value. Even though there are a large number of genotypes with widely varying characteristics, inadequate characterisation and identification result in the lack of awareness, improper utilisation and insufficient post harvest management of avocado. Hence, the present study titled, „Post harvest characterisation and management of avocado (Persea americana Mill.)‟ was carried out in the Department of Post Harvest Technology, College of Agriculture, Vellanikkara during 2018-2021. The main objectives of the study were to characterise avocado accessions collected from different parts of Kerala and to evaluate the effect of post harvest management practices to extend the shelf life of avocado fruits and to study the effect of food additives on the quality of frozen slices, fruit pulp, freeze dried fruit powder and subsequently to standardise an instant avocado fruit shake. For the characterisation of avocado genotypes, 27 accessions were collected, among which 14 accessions were from RARS, Ambalavayal in Wayanad and 12 from Kanthaloor in Idukki and one accession was collected from Thanniyam in Thrissur. Characterisation of avocado genotypes based on the horticultural and biochemical traits, accession 25 from Idukki had comparatively higher TSS, vitamin C, total carbohydrates, total flavonoids, oleic acid, calcium, potassium, iron, total ash and crude fibre content. Hence, accession 25 was selected for subsequent post harvest management studies. Antioxidant activity of the methanolic extract of fresh fruit of accession 25 was evaluated by DPPH, FRAP and ABTS assays. Greatest free radical scavenging activity was observed in ABTS assay with lowest IC50 value of 0.10 μg/mL. Fresh and mature avocado fruits, surface sanitised with 2 ppm ozone and pretreated with 2 % calcium chloride, followed by shrink packaging with 25 μ polyolefin film and subsequently stored in refrigeration (T8) as well as cool chamber (T9) were found to be the ideal storage conditions with longest shelf life of 27 days. Calcium chloride pre-treated fruits with shrink packaging, stored under refrigeration had lowest physiological lossin weight, respiration rate, ethylene evolution rate and decay per cent, with better retention of firmness. Fruits of this treatment retained significantly higher total carbohydrates, total protein and total phenols during storage. Avocado slices pre-treated with 40 % sucrose, ascorbic acid (0.5 %) and potassium metabisulphite (0.1 %), quick frozen to -20 ºCin 30 minutes followed by packing in 200 gauge LDPE pouches and held under frozen temperature (-18 0C) was the most ideal pre-treatment for storage. This treatment recorded significantly higher TSS, vitamin C, total carbohydrates, total protein and organoleptic acceptability throughout storage and lowest water activity, peroxide value and microbial population. For preparation and storage of avocado pulp, pre-treatments with ascorbic acid (0.5%) and KMS (0.1%) followed by vacuum packaging LDPE bags (T10) as well as in glass jars (T12), stored under refrigeration resulted in longest shelf life and better quality. Total protein, total phenols, total carbohydrate, total fat, viscosity and organoleptic scores were highest in these treatments with lowest water activity, polyphenol oxidase activity and microbial population during storage. For preparation of avocado fruit powder, addition of 5% maltodextrin, ascorbic acid (1%), tricalcium phosphate (0.15%), EDTA (0.05%) and potassium sorbate (0.05%) followed by freeze drying at -70 ºCand 100 mtorr vacuum for 36 hours followed by packing in LDPE laminated aluminium pouches (T14) and glass jars (T16) stored under refrigeration were the ideal methods with longest shelf life and quality. Significantly higher bulk density, solubility, colour value L*, TSS, vitamin C, total carbohydrates, total fat and organoleptic scores were recorded in these treatments during storage along with lowest hygroscopicity, colour value a* and b*, peroxide value, water activity and microbial population. An instant avocado shake was standardised by combining avocado fruit powder with skimmed milk powder, sucrose and water in the proportion of 1:2:1:2 with appealing appearance, light yellowish colour, unique blend of taste and flavour of avocado fruit and skimmed milk powder.Item Quality evaluation of avocado (Persea americana) cultivars and suitability of fruit powder for culinary preparations(Department of Community Science, College of Agriculture Vellayani, 2018) Subha S Nair; Anitha Chandran, C